(1) Field of the Invention
The invention relates to a diaphragm valve having a valve body comprising an inlet and an outlet, further having a sealing membrane, and a connecting piece connecting the sealing membrane to a pressure piece of a drive.
(2) Description of Related Art
Diaphragm valves having a valve body comprising an inlet and an outlet are known in the prior art from DE 601 12 639 T2 and DE 20 2005 002 152 U1. The valve bodies further have a valve seat sealed by a sealing membrane, wherein the sealing membrane is connected via a connecting piece to the pressure piece of a drive. The membranes known in the prior art are of double-layer construction.
It is known in the prior art from DE 601 12 639 T2 that the layer facing the valve body is designed as a thin surface-side membrane made of resin containing fluorine and that the second layer is designed as a rear-surface-side membrane which consists of rubber laminated onto the rear side of the surface-side membrane. The connecting piece is an insert that is connected with a positive fit to the thin sealing, or surface-side, membrane.
A disadvantage of this design is that the membrane is fixed by clamps between the valve body and a connection flange of the drive. This means that the process side of the valve can become contaminated during assembly. Similarly, process fluid can unwantedly escape and contaminate the environment during disassembly.
A diaphragm valve is known in the prior art from DE 44 44 782 A1 in which a membrane is fixed between a first housing part and a second housing part designed as a valve body, said membrane being welded ultrasonically to the two housing parts. The membrane is connected directly to a sealing element, via which the valve seat can be sealed. Using a pilot valve, compressed air can be applied to the membrane on the side facing away from the fluid chamber. In the process the membrane with the sealing element is pressed against the force of a return spring arranged on the fluid side and against the valve seat.
A disadvantage of this design is that the housing cannot be disassembled and is not suited to be used as a disposable valve.
Finally, fluid modules designed as micropumps or microvalves are known in the prior art from DE 102 38 585 B3. It is possible to realize as separate elements a fluid part composed of the fluid module and an actuator part to actuate the fluid part, however these are miniaturized one-piece basic elements, the fluid chamber of which can be covered by a planar membrane, which because of the small spacing relative to the valve seat is movable via an actuator designed as a piezo element acting on one side, i.e. the membrane does not have to be rigidly connected to the actuator.
A disadvantage of this design is that fluid modules of this type cannot easily be scaled up and, because of their small flow cross-section, are therefore not suitable for one-time use as valves in tubing systems of filtration systems or bioreactors and tubing systems connected thereto.
A so-called thumb cock designed as a diaphragm valve is known in the prior art from DE 753 C. The diaphragm valve has a valve body with an inlet and an outlet as well as a sealing membrane and a connecting piece connecting the sealing membrane to a pressure piece. The valve body, the sealing membrane, the connecting piece and the drive, and an eccentric disk arranged on a flange, and provided with a thumb-piece or lever, are connected together by screws to form a sealed valve.
A disadvantage of this design is that the membrane is fixed by clamps and screws between the valve body and the flange of the drive. This means that the process side of the valve can become contaminated during assembly. Similarly, process fluid can unwantedly escape and contaminate the environment during disassembly.
Furthermore, a membrane-controlled pressure-regulating valve for fuel control is known in the prior art from DE 197 46 763 A 1, said valve having a housing in which an elastic membrane is fixed by means of a flanged connection between the upper and lower parts of the housing, which form a valve body. The membrane may additionally be welded ultrasonically to the upper or lower housing part. A pressure-regulating spring is located in the upper housing part and presses against a diaphragm disk of the membrane.
A disadvantage of this design is that, on the one hand, the pressure-regulating valve does not have an interchangeable valve body unit and, on the other hand, it cannot be connected to a drive.